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Chinese generic crt tv no b+

Discussion in 'Troubleshooting and Repair' started by MadMann, Oct 9, 2018.

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  1. MadMann

    MadMann

    3
    0
    Oct 8, 2018
    CRT TV Power Supply.jpg

    Hi everyone!
    I'm a beginner in electronics repairing and I need help troubleshooting a tv which doesn't turt on, neither the power LED lights up.

    The board is a cheap chinese (check the attached image). When I opened it and started troubleshooting I found out that the H. O. T was shorted, and the fuse was blown. I made some checking on a few other components and I couldn't find any other fault. So I replaced the defective components (fuse and h.o.t).

    Then I powered it up through a 60W series bulb but it didn't turn on, so I measured some voltages, the readings are as follows:
    Mains Filter - 315V, H.O.T Vce - 315V, R531 was open, I replaced it. I traced the voltage from R520 and it's dead (0) after R522 (check the attached image). And THERE'S NO VOLTAGE ON THE SECONDARY SIDE. Can someone help me by explaining what's going on AND/OR what to do?
     
  2. 73's de Edd

    73's de Edd

    3,070
    1,299
    Aug 21, 2015
    Sir MadMann . . . .

    In ADDITION to your crashed V513-2SC5297 . . .could its failure have taken out V512- 2SC2655 / 2SC3807, by then leaving it with a C-E direct short ? That would pretty well bleed down all of the voltage from that mentioned juncture ?

    73's de Edd
    .....
     
    Richard9025 likes this.
  3. MadMann

    MadMann

    3
    0
    Oct 8, 2018
    V512 is not shorted. I removed it and tested it offboard, when on board and powered up it tests Vce=15v. I even tested the power when it V512 was offboard and still the reading is the same.
     
  4. MadMann

    MadMann

    3
    0
    Oct 8, 2018
    Is 15V the right voltage on the R521 ✖ RR522 ✖ VD514 junction? If not what's supposed to be the right one?
     
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